Gary A. Vaszquez/US PresswireJason Bay remained in Friday night's game after colliding with an outfield wall. He played Saturday and Sunday, too.

NEW YORK – Four days after he smashed into a Dodger Stadium wall, Mets outfielder Jason Bay was diagnosed by team doctors with a “mild” concussion before Tuesday’s game against St. Louis. Bay will be evaluated over the next two to three days, he said, and the team will make a decision on his status at that point.

Either way, he expects to miss about a week of play: Two to three days without baseball activity, then a few days to get re-acclimated to the game.

Right now, he is deal with “just a constant, little, annoying headache.” Doctors are waiting for those to subside. “When the headaches go away, Bay said. “I can ramp up activity.”

On Friday, en route to glove a drive from Dodgers outfielder Jamey Carroll, Bay collided with the left-field bullpen wall. His head snapped back, creating a whiplash effect, he said later. He held on to the ball after the crash. He felt back in his back and knee, but little discomfort in his face.

He first reported symptoms on the team’s flight home –an unfortunate reminder of 2008, when Ryan Church flew across the country with a concussion. But manager Jerry Manuel said he first learned of the diagnosis this morning. The headaches did not begin, Bay insisted, until he was on the plane.

In his place, Jeff Francoeur will regain playing time. This complicates the trade deadline plans of the club. With Carlos Beltran’s return and Angel Pagan’s emergence, Francoeur became involved in trade discussions. But without Bay, he is needed in the lineup.

***
More fallout from that Friday in Los Angeles: Manager Jerry Manuel was suspended one game in response to his ejection from that’s night game. He will serve the suspension on Tuesday. While arguing a call at first base that night, Manuel bumped first-base umpire Doug Eddings.

Bench coach Dave Jauss will run the club in Manuel’s place.

***
The Mets coaching staff remained intact through a meeting-filled Monday, a proposition that seemed in danger the day before after general manager Omar Minaya refused to guarantee the staff would remain in place. For now, hitting coach Howard Johnson is safe.

Manuel, of course, defended his staff to reporters on Tuesday, offering to jump on his sword in turn.

“I think when you go through these things, I think you have to look here,” he said. “You have to look at the manager. I don’t think it’s fair to put other people out there. I think you have to look at the manager. That’s part of it. That’s part of the job. That’s part of being in New York. That’s just what it is. This is who you have to look at. Not the other people.”

Later, when discussing the organizational pressure for urgency, he continued in a similar vein.

“We’ve had discussions with the front office, the hierarchy. They’re as displeased with that and as frustrated with where we are than anybody. Not very happy about what’s going on. So in that scenario, the urgency is here. So to speak.

“And our guys have worked tremendously hard. We’re trying to all we can, baseball-wise, to get through this. But, again, like I said, we all have different responsibilities. But wins and losses, those are my responsibility. You can point at different things. But you’ve got to look at the manager.”

Hisanori Takahashi’s next start was skipped to keep ace Johan Santana on his regular schedule. Santana starts on Wednesday night. Takahashi now will start on Saturday (against dastardly Diamondbacks starter Barry Enright, who stymied the Mets in Phoenix last week). Takahashi will be available from the bullpen on Tuesday.